I just followed this, for a CentOS 5 system and it took right off:

http://wiki.ampr.org/index.php/AMPRNet_VPN

Make sure you have these files in your /etc/openvpn directory: amprnet-vpn-ca.crt client.conf client.crt client.key

Actually with a modern openvpn client it is possible to combine everything in a single .conf file. (or .ovpn when you want to use it on Windows)

The certificates and keys van be put in the file "inline". I use this method for distribution of openvpn configs that can be used with our national VPN gateway (only available for Dutch stations), for which we generate certificates and send them to the users.

The file for the amprnet vpn system would look like this:

client dev tun proto udp remote amprnet-vpn1.aprs.fi 1773 resolv-retry infinite persist-key persist-tun comp-lzo verb 3

ca [inline] cert [inline] key [inline]

<ca> contents of the amprnet-vpn-ca.crt file </ca>

<cert> contents of the client.crt file </cert>

<key> contents of the client.key file </key>

This makes it easier to move the certificate around, use it on Windows, etc. Only really old versions of the openvpn client, today only found on devices like NAS that have not updated for a long time, do not support the [inline] construct.

Rob